An important step in integrated circuit manufacturing is the processing of the semiconductor substrate in which active devices such as transistors and capacitors that comprise the integrated circuits are formed. In the course of forming integrated circuit structures on semiconductor wafers, certain processes are utilized that may take place in enclosed chambers into which the wafer is carried and within which the wafer is held during processing. Some of these processes include, for example, growth of an epitaxial silicon layer, the formation of a thermal oxide or thermal nitride layer over silicon, the rapid thermal annealing of integrated circuit structures already formed on the wafer, etc. Generally, the wafer is held in a horizontal position during processing. Typically, a platform such as a susceptor, or a wafer carrier or lifting mechanism may be used for supporting the wafer horizontally.
One example of a processing chamber includes a platform on which the substrate (or more specifically, wafer) rests during processing. One type of platform commonly used in an epitaxial atmospheric chamber is known as a susceptor. The processing chamber can also include a substrate carrier which carries the substrate onto the platform or lifts the substrate from the platform. Together, the platform (susceptor, for example) and substrate carrier can be referred to as a substrate support assembly. The substrate carrier typically includes pins or arms that extend upwardly through apertures in the susceptor. When the substrate (or wafer) is inserted into the processing chamber, it is placed onto the tops of the upwardly extended pins or arms such that it is spaced apart from the surface of a pocket defined at the top of the susceptor. Then the pins or arms are either lowered such that the wafer is lowered to the surface of the susceptor pocket, or the body of the susceptor can be raised to the level of the wafer while the pins or arms remain stationary. The pins can contact the wafer at points inwardly from the wafer's edge, or the arms or pins can engage the wafer near its edge or periphery.
The pins or arms can be fabricated out of quartz, for example. The atmosphere within a processing chamber can be very harmful to materials such as quartz and can shorten the life span of parts made from such materials. During the creation of the silicon layers on the wafer, for example, corrosive gases in combination with high temperatures and extremely wide variations in temperature are used. One example of a potentially harmful gas is gaseous hydrochloric acid (HCl). Also, the quartz parts are periodically cleaned with aqueous hydrofluoric acid (HF), for example. These environmental factors can be destructive to quartz, especially when relatively small and intricate details are machined into the quartz pins or arms.
Replacement of worn quartz parts can be expensive and time consuming. For example, when a substrate carrier needs to be replaced, the processing chamber must be disassembled and is out of service for a period of time. Thus, it is desirable to provide parts that are durable in the harmful environment of semiconductor processing chambers.
Silicon carbide (SiC) has proven to be a more robust material than quartz in epitaxial atmospheric chambers, for example. The use of SiC on the tips of the quartz arms is desirable because SiC is more durable in the harmful atmosphere of the processing chamber than quartz.
Thus, what is needed is a novel apparatus that provides a durable yet geometrically and dimensionally precise support arm or pin for a substrate support or carrier.